The present invention relates to a yarn winding machine for winding a filament yarn, of the type generally disclosed in DE-OS 36 103 68. Such winding machines are suitable for winding speeds of more than 6,000 meters per minute, and they typically comprise a rotatable spindle adapted for having a bobbin supported yarn package wound thereupon, and a contact roll which is mounted for rotation about an axis parallel to that of the spindle and which is adapted to engage the surface of the package being wound on the spindle. Also, the contact roll is mounted by a carriage which lifts it from the surface of the package during the package doffing process.
It is, furthermore, recognized that the yarn transfer operation during the package doff at the indicated high winding speeds may lead to malfunctions, in that so-called laps are formed on the roll. Therefore, also a separate braking mechanism is provided for slowing the speed of rotation of the contact roll.
It is an object of the present invention to provide a yarn winding machine which permits the speed of the contact roll to be accurately and efficiently controlled when it is lifted from the winding spindle, so as to provide alternately optimum rotational speed or braking during the doffing process.
In view of the high speed, no slippage should occur between the yarn and the contact roll during the doffing operation. Therefore, the contact roll has been coupled with a turbine which drives the contact roll during the package doff and which maintains a constant speed.